SC2: states of matter & mixtures Flashcards

1
Q

the kinetic particle theory

A

describes the arrangement, movement & energy of particles in a substance

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2
Q

how do solid particles vibrate?

A

around a fixed point

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3
Q

what energy do solids have?

A

low

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4
Q

how close are the particles in a solid?

A

very close

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5
Q

what pattern do solids have?

A

regular

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6
Q

energy in liquids

A

liquids have greater energy than solids

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7
Q

how do liquids move?

A

slide past each other

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8
Q

how are liquids arranged?

A

randomly

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9
Q

how close are liquid particles?

A

quite close

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10
Q

how much energy do gases have?

A

highest

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11
Q

how do gas particles move?

A

quickly and randomly

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12
Q

how close are gas particles?

A

far apart

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13
Q

what arrangement do gases have?

A

random

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14
Q

can solids be compressed?

A

no, they are close together and have no space to move into

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15
Q

can solids flow?

A

no as particles have nowhere to move

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16
Q

do solids have a definite shape and volume?

A

yes

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17
Q

do liquids have fixed volume and shape?

A

fixed vol not shape

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18
Q

can liquids be compressed?

A

not easily as their particles are close

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19
Q

can liquids take the shape of containers?

A

yes as they can flow

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20
Q

can gases be compressed?

A

yes as particles are far away from each other and have lots of space to move into

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21
Q

do gases have a definite shape or volume?

A

no

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22
Q

can gases take the shape of a container?

A

yes, as particles move quickly in all directions

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23
Q

changes of state

A

transformations of matter from one state to a different one (physical change only, no more substances made)

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24
Q

melting

A

solid to liquid

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25
Q

evaporate

A

liquid to gas

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26
Q

freezing

A

liquid to solid

27
Q

condense

A

gas to liquid

28
Q

sublimation

A

a change directly from the solid to the gas without becoming liquid

29
Q

melting, evaporation & boiling

A

-particles in the solid have enough energy to overcome the forces between them
-they break out of fixed arrangement and move more freely

30
Q

condensing & freezing

A

-energy is transferred from a substance to the surroundings when a substance
-the particles lose energy and bonds form between particles

31
Q

what is particle theory?

A

scientists understanding of solids, gases & liquids

32
Q

what are some limitations of particle theory?

A

-it doesn’t consider the forces between molecules
-it assumes that all particles are spheres even though particles have complex shapes

33
Q

predicting a physical state

A

-state of a substance at a given temp can be predicted if it’s melting point & boiling point are known
-if given temp is less than melting point, then it’s a solid
-if given temp between melting & boiling points then it’s a liquid
-if given temp larger than boiling point then it’s a gas

34
Q

pure substance

A

only one element or compound

35
Q

mixture

A

two or more substances that are not chemically combined

36
Q

element

A

only contains one type of atom

37
Q

compound

A

2 or more elements chemically combined

38
Q

what melting point does a pure substance have?

A

sharp

39
Q

what melting point does a mixture have?

A

melts over a range of temperatures

40
Q

when a pure substance changes state the temperature…

A

stays the same

41
Q

when an impure substances changes state the temperature…

A

changes slightly

42
Q

filtration

A

used to separate an insoluble solid from a liquid

43
Q

why does filtration work?

A

the filter paper has tiny holes that are big enough to let small molecules and dissolved ions through

44
Q

crystallisation

A

-used to produce solid crystals from a solution
-when the solution is warmed, some of the solvent evaporates and leaves a concentrated solution

45
Q

solution

A

a mixture that forms when one substance dissolves another

46
Q

solute

A

the substance that is dissolved

47
Q

solvent

A

the substance in which the solute dissolves

48
Q

how to obtain large, regularly shaped crystals in crystallisation?

A

-put the solution to into an evaporating basin
-warm it by placing the basin over a bunsen burner
-stop all the heating b4 the solvent evaporates
-pour excess liquid away & dry the crystals

49
Q

simple distillation

A

-used to separate a solvent and solute in a solution
-the dissolved solute has a higher boiling point than the solvent, so when the solution is heated, solvent vapour evaporates from the solution, gas moves and cools & condense

50
Q

simple distillation steps

A
  1. the water is heated
  2. water vapour is produced
  3. water vapour cools, condenses & drops into the beaker
  4. the water is condensed & the salt stays behind
51
Q

fractional distillation

A

-used to separate different liquids from a mixture of liquids
-works because different liquids have different boiling points
-vapour rises through a column which is hot at the bottom and cold at the top, the vapour condenses when it reaches a part of the column that’s below its boiling point
-liquid flows out of the column

52
Q

paper chromatography

A

separates the mixtures of soluble substances

53
Q

paper chromatography steps

A
  1. water & ethanol solution is heated (the solvent)
  2. as the paper is lowered into the solvent, some dye spreads up the paper
  3. the paper has absorbed the solvents & dye had spread further up the page
54
Q

stationary phase

A

the phase that does not move in chromatography (eg: paper)

55
Q

the mobile phase

A

the solvent that moves through the paper & carries different substances with it

56
Q

why do different substances move at different rates in chromatography?

A

-the different dissolved substances in a mixture are attracted to the two phases in different proportions
-this causes them to move at different rates through the paper

57
Q

what does separation by chromatography produce?

A

-a chromotogram
-a paper chromatogram can be used to distinguish between pure and impure substances

58
Q

how many dots would a pure and impure substance have?

A

pure = 1
impure = 2 or more

59
Q

how can you tell if substances are the same in chromatography?

A

they have the same amount of spots, match in colour and travel the same distance up the paper

60
Q

how to calculate the rf value

A

distance travelled by substance / distance travelled by solvent

61
Q

paper chromatography steps

A
  1. draw pencil line across paper 1-2cm from bottom
  2. use pipette to add small spots of ink to the pencil line on paper
  3. place the paper into a container with a suitable solvent in the bottom
  4. allow the solvent to move through the paper and remove the chromatogram before it reaches the top
  5. allow chromatogram to dry, then measure the distance travelled by each spot and distance
62
Q

treating fresh water (steps)

A

-large objects removed by screening using grids
-coarse filter removes larger insoluble grit particles
-aluminium sulfate is added to clump smaller insoluble particles together, these settle in the bottom of a sedimentation tank
-a fine filter bed removes very small insoluble particles
-chlorine gas is added to kill harmful microorganisms

63
Q

treating seawater

A

-seawater contains too much dissolved salt to be suitable for drinking

simple distillation used to treat it:
-seawater is boiled & the water vapour is lead away & cooled
-it condenses to form pure water, leaving the salt behind

64
Q

facts about the distillation process

A

-expensive as large amounts of energy are needed to heat the seawater
-water produced by distillation is useful in the laboratory for dissolving substances (does not contain any dissolved ions that might interfere with a chemical analysis)